This invention relates to mounting systems for industrial lighting fixtures and more particularly to such systems for hanging light fixtures from overhead structures.
It is often desirable to suspend electrical lighting fixtures from overhead structures such as ceilings or exposed ironwork. Typically, in order to meet certain safety regulations, the electrical wiring to the lighting fixture must be run through metal conduit and metal junction boxes. The junction boxes are used where the pieces of conduit or the wires within the conduit must be joined. Often, the conduit and junction boxes are used to provide the mechanical structure by which to suspend the light from the overhead structure.
For example, a junction box is attached to an overhead structure by means of screws or other threaded fasteners. A conduit with electrical supply wires is run through the conduit and the wires are thus terminated within the box. The lamp assembly is mechanically suspended from the junction box and the wires connected to the lamp are spliced to the electrical supply wires within the junction box. The box is not always mechanically connected directly to the overhead structure but may be suspended from it by means of a pipe or second electrical conduit.
The installation of such lighting systems is time consuming and somewhat dangerous. The junction box must first be installed either on or suspended from the overhead structure with the electrical supply wires terminated within the box. In practice this will mean that such a box is located high above the floor of the room. The fixture must be carried up a ladder or scaffold by the electrician installing it and he must make the mechanical and electrical connections between the junction box and the lamp. Usually the junction box is open at the bottom and the lamp is attached to a plate which can be fixed, by means of screws, to the bottom of the junction box. Short lengths of wire from the electrical supply are located in the junction box and corresponding short wires from the lamp assembly are positioned at the side of the plate which will be enclosed in the box. The electrician must hold the plate with the lamp attached in close proximity to the box while splicing the wires. This operation is often carried out in precarious conditions. Depending on circumstances, it may require that the electrician balance the lamp on the ladder, that he hold it in one arm while splicing the wires with the other, or that he enlist the aid of a helper to position the lamp and plate.
After the wires are spliced, the plate must be secured to the box by means of screws or other threaded fasteners. Again this is awkward since the screws must be fitted while the plate and lamp are held in proper alignment with the box. There is the possibility that the screws, the lamp, or tools will be dropped. Even worse, the operation often requires the electrician to assume an awkward and unbalanced position on top of the ladder or scaffold. This causes an increase in the likelihood that he will fall.
The above mentioned shortcomings are not only present when the fixture is installed. The lighting fixtures sometimes have to be removed for repair or the wires within the junction box must be inspected. In such cases the junction box must be opened. If the fixture is to be removed the wires must be disconnected.
For all their shortcomings, the mounting systems described above are relatively sturdy once assembled since the various parts are attached to the junction boxes with screws. There is little danger of the plate and connected lighting fixture becoming dislodged due to inadvertent acts of the electrician, vibration, or objects striking the fixture.
It would be advantageous to retain the sturdiness of the mounting systems presently in use while overcoming their shortcomings.
Hence, an object of the present invention is to provide new and improved mounting systems for suspended lighting fixtures which enables rapid, convenient and safe installation or removal.
A further object is to provide mounting systems for suspended lighting fixtures which may be assembled or disassembled while workmen are above ground without the use of tools.
Also an object of the invention is to provide for suspended lighting fixtures, by means of a plate attached to a lamp assembly so that the plate may be pivotably attached to the remainder of a junction box while allowing access to the interior of the box and to the wires therein and which thereafter may be closed without the use of tools.
It is yet another object to provide mounting systems for suspended lighting fixtures, in a manner which requires components to be moved in two different directions in order to close or open and thereby prevent inadvertant dislodgement of the component parts.